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Abstract:

A method for operating a water-conducting household appliance having a
storage container which is connected by means of an overflow outlet in a
liquid-conducting manner to a washing compartment and having a pump which
is connected in the liquid-conducting manner to the washing compartment.
The method includes starting the pump; filling the storage container with
a liquid; monitoring a first operating parameter associated with the pump
after the pump has been started; and terminating the filling of the
storage container with the liquid when the first operating parameter
reaches a predefined threshold value and/or the first operating parameter
exceeds a predefined fluctuation range.

Claims:

1-18. (canceled)

19. A method for operating a water-conducting household appliance having a
storage container which is connected by means of an overflow outlet in a
liquid-conducting manner to a washing compartment and having a pump which
is connected in the liquid-conducting manner to the washing compartment,
the method comprising:starting the pump;filling the storage container
with a liquid;monitoring a first operating parameter associated with the
pump after the pump has been started; andterminating the filling of the
storage container with the liquid when at least one of the first
operating parameter reaches a predefined threshold value and the first
operating parameter exceeds a predefined fluctuation range.

20. The method of claim 19, wherein the water-conducting household
appliance is one of a dishwasher and a washing machine.

21. The method of claim 19, wherein the storage container is connected to
the washing compartment in a heat-conducting manner.

22. The method of claim 19, wherein the storage container is connected to
an external wall of the water-conducting household appliance in a
heat-conducting manner.

23. The method of claim 19, wherein the liquid is delivered by means of
the pump to spraying devices disposed inside the washing compartment.

24. The method of claim 19, further comprising:starting a drive driving
the pump; andmonitoring a second operating parameter of the drive.

25. The method of claim 24, wherein the drive has an electric motor.

26. The method of claim 25, wherein the electric motor is a brushless
three-phase synchronous motor.

27. The method of claim 24, wherein the second operating parameter is at
least one of a first electric power output of the drive, an electric
current of the drive, an electrical voltage of the drive, a torque that
is to be generated by the drive, and a rotational speed of the drive.

28. The method of claim 27, wherein one of:the second operating parameter
is the electric current of the drive, wherein the predefined threshold
value is associated with an electric current intensity that is greater
than a drive electric current intensity of the drive when the pump is
essentially running only in air and that is less than the drive electric
current intensity of the drive when the pump is pumping the liquid
essentially continuously; andthe second operating parameter is the first
electric power output of the drive, wherein the predefined threshold
value is associated with a second electric power output that is greater
than the first electric power output of the drive when the pump is
essentially running only in air and less than the first electric power
output of the drive when the pump is pumping the liquid essentially
continuously.

29. The method of claim 19, further comprising additional pumping out of
the liquid contained in the washing compartment before at least one of
the storage container is filled with the liquid and the pump is started.

30. A water-conducting household appliance, comprising:a storage
container;a washing compartment;an overflow outlet connecting the storage
container to the washing compartment in a liquid-conducting manner;a pump
connected to the washing department in the liquid-conducting manner; anda
control device to start the pump one of before and during a filling
operation of the storage container, the control device to monitor a first
operating parameter associated with the pump, and the control device to
terminate the filling operation when at least one of the first operating
parameter reaches a predefined threshold value and the pump operating
parameter exceeds a predefined fluctuation range.

31. The water-conducting household appliance of claim 30, wherein the
water-conducting household appliance is one of a dishwasher and a washing
machine.

32. The water-conducting household appliance of claim 30, wherein the
storage container is connected to the washing compartment in a
heat-conducting manner.

33. The water-conducting household appliance of claim 30, wherein the
washing compartment has an external wall, and wherein the storage
container is connected to the external wall of the washing compartment in
a heat-conducting manner.

34. The water-conducting household appliance of claim 30, further
comprising spraying devices disposed inside the washing compartment,
wherein the pump is structured to deliver the liquid to the spraying
devices.

35. The water-conducting household appliance of claim 30, further
comprising a drive having a second operating parameter, wherein the first
operating parameter associated with the pump is the second operating
parameter of the drive.

36. The water-conducting household appliance of claim 35, wherein the
drive has an electric motor.

38. The water-conducting household appliance of claim 35, wherein the
second operating parameter is at least one of a first electric power
output of the drive, an electric current of the drive, an electrical
voltage of the drive, a torque that is to be generated by the drive, and
a rotational speed of the drive.

39. The water-conducting household appliance as claimed in claim 38,
wherein one of:the second operating parameter is the electric current of
the drive, wherein the predefined threshold value is associated with an
electric current intensity that is greater than a drive electric current
intensity of the drive when the pump is essentially running only in air
and that is less than the drive electric current intensity of the drive
when the pump is pumping the liquid essentially continuously; andthe
second operating parameter is the first electric power output of the
drive, wherein the predefined threshold value is associated with a second
electric power output that is greater than the first electric power
output of the drive when the pump is essentially running only in air and
less than the first electric power output of the drive when the pump is
pumping liquid essentially continuously.

40. The water-conducting household appliance of claim 28, further
comprising a second pump to pump out the liquid contained in the washing
compartment, wherein the control device is structured to start the second
pump before at least one of a valve is opened and the drive is started.

Description:

[0001]The invention relates to a method for operating a water-conducting
household appliance, in particular a dishwasher or washing machine.

[0002]DE 38 03 006 A1 discloses a dishwasher having a washing compartment,
a water inlet valve for filling the washing compartment with liquid, a
spraying device disposed in the washing compartment, a circulation pump
for delivering the liquid to the spraying device, and an electric motor
for driving the circulation pump. In order to ensure that there is
currently a sufficient amount of liquid in the washing compartment to
enable the circulation pump to deliver the liquid without entrapped air
to the spraying device, DE 38 03 006 A1 discloses that after completion
of a filling operation to fill the washing compartment to a minimum level
with the liquid the water inlet valve for filling the washing compartment
will be closed when a constant measurement value for the current
consumption of the electric motor for the circulation pump has been
reached.

[0003]DE 42 33 643 C2 discloses a dishwasher having a washing compartment
and a storage container connected in a heat-conducting manner to the
washing compartment for the purpose of provisioning liquid that is to be
used in a subsequent subprogram of an overall program of the dishwasher.
Owing to the heat-conducting connection between the washing compartment
and the storage container the liquid contained in the storage container
is preheated for the subprogram.

[0004]The object of the present invention is therefore to disclose a
simplified method for detecting a full storage container of a
water-conducting household appliance.

[0005]The object of the invention is achieved by means of a method for
operating a water-conducting household appliance, comprising the
following method steps of: [0006]filling the storage container with
liquid, [0007]starting the circulation pump, [0008]monitoring at least
one operating parameter associated with the circulation pump, and
[0009]terminating the filling of the storage container with liquid when
the operating parameter reaches a predefined threshold value and/or when
the operating parameter exceeds a predefined fluctuation range.

[0010]The object of the invention is also achieved by means of a
water-conducting household appliance having the features recited in claim
10.

[0011]The water-conducting household appliance according to the invention
has a storage container which is connected to the washing compartment, in
particular in a heat-conducting manner, in that it is secured e.g. to a
wall of the washing compartment. During the operation of the dishwasher
the storage container is filled with liquid, e.g. with water from a water
supply line until it is full. Toward that end the control device, which
has, for example, a suitably programmed microprocessor, opens the valve.
Once the storage container is completely filled with liquid, the excess
liquid flows e.g. via an overflow outlet from the storage container into
the washing compartment. The storage container can also be connected in a
heat-conducting manner to an external wall of the water-conducting
household appliance.

[0012]In the washing compartment there can be disposed a spraying device,
e.g. in the form of spray arms, to which, in the case of a dishwasher, a
pump serving as a circulation pump delivers liquid contained in the
washing compartment during the dishwasher's operation. The circulation
pump is driven e.g. by means of a drive. The latter has e.g. an electric
motor which, for example, is controlled by suitable electronics or power
electronics. The electric motor can be, for example, a three-phase motor,
in particular a brushless synchronous motor.

[0013]According to the inventive method the pump is started in particular
as a result of the control device starting the drive. During the filling
of the storage container only relatively little liquid, if any, is
contained in the washing compartment. According to a variant of the
inventive method this is ensured in that before the storage container
begins to be filled with liquid and/or before the circulation pump or, as
the case may be, the electric drive is started, liquid contained in the
washing compartment is pumped out. This can be accomplished e.g. by
starting a drain pump provided for the purpose of pumping out the liquid
contained in the washing compartment, said pump being switched on in
particular by the control device.

[0014]As just mentioned, before the storage container is filled there is
only relatively little liquid, if any, in the washing compartment.
Consequently the circulation pump initially runs in air and has a
relatively small and a relatively constant power draw or, as the case may
be, generates a relatively small and relatively constant torque. If the
storage container is full and nonetheless continues to be supplied with
liquid, the excess liquid flows into the washing compartment via an
overflow outlet for example. Said liquid reaches the pump in the intended
manner, as a result of which there is a change in the operating
performance of the pump or, as the case may be, of the electric drive
driving the pump. If the storage container continues to be filled with
liquid, more and more liquid flows into the washing compartment until the
pump is pumping liquid essentially continuously, as a result of which the
pump has a higher, though likewise relatively constant power draw or, as
the case may be, generates a higher, though relatively constant torque.
During the time interval in which, although liquid is flowing into the
washing compartment, there is not yet a sufficient volume thereof, with
the result that the pump is pumping liquid essentially continuously, the
power draw or, as the case may be, the torque increases on the one hand.
However, these operating parameters also fluctuate to a relatively great
degree because the pump is pumping both liquid and air.

[0015]Accordingly it is provided according to the invention to monitor the
at least one operating parameter associated with the pump and to
terminate the filling of the storage container when the operating
parameter reaches the predefined threshold value and/or when the
operating parameter exceeds the predefined fluctuation range. If this is
the case it can be assumed that the storage container is completely
filled with liquid, as a result of which the control device of the
water-conducting household appliance according to the invention
terminates the filling operation.

[0016]The pump, in particular the circulation pump, is driven by the
electric drive, for example. According to an embodiment variant of the
inventive method or, as the case may be, of the inventive
water-conducting household appliance, such as e.g. a dishwasher, the
operating parameter associated with the circulation pump is an operating
parameter of the electric drive driving the circulation pump. The
operating parameter of the electric drive is e.g. its electric power
output, an electric current of the electric drive, an electrical voltage
of the electric drive, a torque that is to be generated by the electric
drive and/or a rotational speed of the electric drive. These operating
parameters can be determined relatively easily during the operation of
the dishwasher, in particular when the drive is an electronically
controlled drive, which means that the method according to the invention
can be implemented relatively easily. It can also be provided to regulate
or control the electric drive. In such a case an operating parameter of
the electric drive or of the circulation pump is required for said
control or regulation, which operating parameter can then also be used
for detecting when the storage container is completely filled with
liquid. In such a case the electric current or the electric power output
of the electric drive or motor of the electric drive in particular lends
itself to use as the operating parameter requiring to be monitored.

[0017]In the case of a variant of the inventive method or, as the case may
be, of the water-conducting household appliance, e.g. of a dishwasher
according to the invention, in which the operating parameter is the
electric current of the electric drive, the threshold value can be
associated in particular with an electric current intensity which is
greater than the intensity of the electric current of the electric drive
when the circulation pump is essentially running only in air, and less
than the intensity of the electric current of the electric drive when the
circulation pump is pumping liquid essentially continuously. In the case
of the variant of the inventive method or, as the case may be, the
inventive dishwasher in which the operating parameter is the electric
power output of the electric drive, the threshold value can be associated
with an electric power output which is greater than the electric power
output of the electric drive when the circulation pump is essentially
running only in air, and less than the electric power output of the
electric drive when the circulation pump is pumping liquid essentially
continuously. According to these embodiment variants it can thus be
ensured that on the one hand the storage container is completely full
before the valve is closed. On the other hand, according to these
embodiment variants, a relatively strong overflowing of the storage
container can be prevented.

[0018]By means of the inventive method or, as the case may be, the
inventive dishwasher it is accordingly possible to detect a full storage
container in particular without a special switch which detects when the
storage container is completely filled with liquid.

[0019]An exemplary embodiment is illustrated by way of example in the
attached schematic drawings, in which:

[0021]FIG. 2 shows a schematic diagram of the dishwasher having a
circulation pump and a storage container,

[0022]FIG. 3 shows a signal waveform associated with the circulation pump,
and

[0023]FIG. 4 is a flowchart for illustrating a method for filling the
storage container.

[0024]FIG. 1 shows a dishwasher 1 and FIG. 2 shows a schematic diagram of
the dishwasher 1. The dishwasher 1 has a washing compartment 2 for
accommodating items to be washed, e.g. dirty dishes and cutlery, which
are arranged, for example, in an upper dishwasher basket 3 and a lower
dishwasher basket 4. Disposed in the washing compartment 2, which is
manufactured, for example, from metal, e.g. from chrome, steel or
chromium-nickel steel, are spraying devices, e.g. generally known spray
arms 5 for spraying the items to be washed with a liquid which is usually
referred to as washing liquor. Located in the base of the washing
compartment 2 is a sump 24 in which a circulation pump 23 is disposed.
Liquid from the washing compartment 2 reaches the circulation pump 23 via
the sump 24, as indicated by means of an arrow 25 in FIG. 2. The
circulation pump 23 in turn pumps the liquid to the spray arms 5, as
indicated by means of an arrow 26 in FIG. 2.

[0025]The washing compartment 2 is disposed in a housing 6 of the
dishwasher 1 and comprises two sidewalls. The sides of the sidewalls of
the washing compartment 2 pointing into the interior of the washing
compartment 2 are visible when the door 7 of the dishwasher 1 is open.
When the door 7 is open the upper dishwasher basket 3 and the lower
dishwasher basket 4 can be withdrawn from the washing compartment 2.

[0026]In the case of the present exemplary embodiment there is disposed
between one of the sidewalls of the washing compartment 2 and the
corresponding sidewall of the housing 6 a storage container 8 for liquid,
in particular for fresh water, which storage container acts as a heat
exchanger. The storage container 8 is connected to the relevant sidewall
of the washing compartment 2 in a heat-conducting manner such that the
liquid contained in the storage container 8 is heated by the heated
liquid in the washing compartment 2. The storage container 8 is, for
example, in direct contact through one of its sidewalls with the relevant
sidewall of the washing compartment 2 and is e.g. screwed or clipped to
said sidewall.

[0027]The storage container 8 has a liquid inlet 11 and an outlet 10 for
discharging the liquid of the storage container 8 into the washing
compartment 2. A flowmeter 12 is connected upstream of the liquid inlet
11 and upstream of the flowmeter 12 there is connected in turn a filling
valve 13 by means of which, in the case of the present exemplary
embodiment, the storage container 8 can be filled with fresh water from a
water supply line 14. Connected downstream of the outlet 10 is an outlet
valve 15 by means of which the liquid from the storage container 8 can be
discharged in a controlled manner into the washing compartment 2. The
storage container 8 also has an overflow outlet 9 via which excess liquid
from the storage container 8 can flow into the washing compartment 2.

[0028]The dishwasher 1 additionally has a control device 16 which has e.g.
a suitably programmed microprocessor. The control device 16 is supplied
with electrical energy in a manner that is not shown and is connected by
means of an electric cable 17 to the filling valve 13 and by means of an
electric cable 19 to the outlet valve 15, such that the control device
16, with the aid of a computer program running on same, can open and
close the filling valve 13 and the outlet valve 15 in order to control
the filling of the storage container 8 with liquid from the water supply
line 14 and a flowing of the liquid out of the storage container 8 into
the washing compartment 2.

[0029]The volume of liquid flowing into the storage container 8 can be
measured by means of the flowmeter 12 which is connected to the control
device 16 via an electric cable 18.

[0030]The dishwasher 1 additionally has an electric drive 22, the electric
motor of which drives the circulation pump 23 via a shaft 21. In the case
of the present exemplary embodiment the motor of the electric drive 22 is
what is referred to as a BLDC motor, i.e. a brushless DC three-phase
synchronous motor. The electric drive 22 also has an inverter which
supplies the electric motor of the electric drive 22 with electrical
energy. The inverter generates the three-phase electrical voltage
required for the motor, i.e. the required frequency and the required
root-mean-square value of the electrical voltage. Suitable inverters have
e.g. power semiconductors and are generally known to the person skilled
in the art, for which reason the inverter is not shown explicitly and
also will not be explained in further detail.

[0031]The electric drive 22 is connected to the control device 16 by means
of an electric cable 20 such that the control device 16 can control and
if necessary also regulate the inverter or, as the case may be, the
electric drive 22 in a generally known manner.

[0032]The control device 16 also receives information about at least one
operating parameter of the electric drive 22 by way of the electric cable
20. The operating parameter of the electric drive 22 can be used e.g. for
controlling or, as the case may be, regulating the electric drive 22. In
the case of the present exemplary embodiment the operating parameter is
the electric power output of the electric drive 22 or the electric
current i of the motor of the electric drive 22. FIG. 3 shows a waveform
of the electric current i by way of example.

[0033]In the case of the present exemplary embodiment the electric current
i of the electric motor is used in order to detect a full storage
container 8. A flowchart shown in FIG. 4 summarizes the method used in
the case of the present exemplary embodiment for filling the storage
container 8 with liquid.

[0034]Shortly before the storage container 8 is filled with liquid from
the water supply line 14 there is no liquid in the washing compartment 2
and the circulation pump 23 is started as a result of the electric drive
22 of the circulation pump 23 being started at time t0 (FIG.
3)--step A of the flowchart. The liquid has been pumped out of the
washing compartment 2 e.g. by means of a drain pump that is not shown but
is generally known. Since there is no or, if any, only a relatively small
amount of liquid in the washing compartment 2, i.e. the sump 24 is also
empty, the circulation pump 23 is running in air. The power draw of the
electric drive 22, and hence also the electric current i of the electric
motor, is accordingly relatively low and also relatively constant.

[0035]Simultaneously with the starting of the circulation pump 23, for
example, the control device 16 or, as the case may be, a computer program
running on the control device 16 opens the filling valve 13, as a result
of which liquid from the water supply line 14 flows via the liquid inlet
11 into the storage container 8--step B of the flowchart. The outlet
valve 15 is closed. While the storage container 8 is not yet completely
filled with liquid from the water supply line 14, there is still no
liquid in the washing compartment 2. Accordingly the circulation pump 23
is still running in air and has a relatively low and relatively constant
power draw (no-load power).

[0036]At time t1 the storage container 8 is completely full and
excess liquid from the storage container 8 begins to run via the overflow
outlet 9 of the storage container 8 into the washing compartment 2. Said
liquid reaches the sump 24 and from there flows into the circulation pump
23. The circulation pump 23 begins pumping the liquid, as a result of
which the power draw of the electric drive 22 and consequently the
electric current i of the electric motor start to increase.

[0037]If the filling valve 13 is not closed, more and more liquid flows
into the storage container 8 and hence via the overflow outlet 9 into the
washing compartment 2. As a result the circulation pump 23 pumps more and
more liquid and the electric power output of the electric drive 22 or, as
the case may be, the electric current i of the motor increases until at
time t2 there is so much liquid in the washing compartment 2 that
the circulation pump 23 can pump liquid essentially continuously. From
time t2 there is therefore once again a relatively constant power
draw which is substantially greater than the no-load power of the
electric drive 22. The electric current i of the electric motor is
accordingly relatively constant from time t2 and greater than the
electric current i prior to time t1.

[0038]In the time interval between t1 and t2 there is in fact
liquid in the washing compartment 2. The amount of said liquid is not,
however, sufficient for the circulation pump 23 to pump liquid
essentially continuously. To put it more precisely, in the time interval
between t1 and t2 the circulation pump 23 conveys a mixture of
air and liquid, as a result of which the power draw of the electric drive
22, although increasing as the volume of liquid in the washing
compartment 2 increases, also fluctuates relatively strongly. This in
turn causes a relatively strongly fluctuating electric current i of the
electric motor.

[0039]In the case of the present exemplary embodiment the control device
16 or, as the case may be, the computer program running on the control
device 16 monitors the electric current i of the electric motor and
compares this with a previously stored threshold value is --step C
of the flowchart. Said threshold value is lies between the electric
current i during no-load operation and the electric current i starting
from time t2 and in the case of the present exemplary embodiment is
reached at time t3.

[0040]If the control device 16 detects that the electric current i of the
electric motor has reached the threshold value is, it automatically
closes the filling valve 13, thereby stopping the feeding of liquid from
the water supply line 14 into the storage container 8--step D of the
flowchart. This means that a full storage container 8 can be detected in
a relatively simple manner.

[0041]In the case of the described exemplary embodiment the electric
current i of the electric motor of the electric drive 22 for the
circulation pump 23 is monitored for the purpose of detecting a full
storage container 8. Other operating parameters of the electric drive 22
or the circulation pump 23 are also suitable. Further suitable operating
parameters are e.g. the torque of the electric motor or circulation pump
23, an electrical voltage of the electric drive 22, the root-mean-square
value of the generated electrical voltage, for example, or a rotational
speed of the electric motor.

[0042]The full storage container 8 can also be detected as a result of
detecting a relatively large fluctuation in the operating parameter. As
explained hereintofore, the electric current i fluctuates relatively
strongly in the time interval between t1 and t2. Accordingly, a
relatively large fluctuation in the operating parameter can also be used
for detecting a full or, as the case may be, overflowing storage
container 8.

[0043]In the case of the described exemplary embodiment the circulation
pump 23 is driven by the electric drive 22, the motor of which is a
brushless three-phase synchronous motor. Other electric drives for the
circulation pump 23 are also possible. In particular it is not necessary
for the electric drive 22 to be a three-phase current drive.
Direct-current or alternating-current drives, for example, can also be
used.